Tanks of tilapia are the secret to success for New Boston hydroponic greenhouse success
NEW BOSTON -- Starting with some pipes, some plants and his outdoor goldfish pond, Mike Griffin began his journey into the world of hydroponics, and now he's producing vegetables and fish for farmers markets, general stores and restaurants in a single greenhouse.
Hydroponics is a veritable circle of life. In the warmth of a greenhouse, the circle starts with a tank full of fish — in Griffin's case, tilapia. The fish eat food and then create liquid fertilizer which is pumped into a series of planting areas. In the planting beds, the fertilized water feeds the plant and is then cleaned and oxygenated as it passes through gravel beds. The clean water then returns to the fish tanks and the circle of life begins anew.
Griffin first toyed with hydroponics outside, using his decorative goldfish pond at his home in New Boston. During the growing season, he used piping to pull the water through his planting beds and produced more vegetables than he could consume. And the work was easy, said Griffin, because there is minimal weeding, the beds can be raised so there's no bending over to harvest, and no dirt to haul around. The work was essentially done for him — all he had to do was feed the fish and maintain the pumps and pipes. But now he's has turned a hobby into a source of income, and a part-time job.
"I can't keep up with demand," he said. "I'm going to have to build a second greenhouse this year."
Year 'round, Griffin grows salad greens, tomatoes, peppers; onions and other root vegetables like beets and turnip; even nasturtium — an edible flower that restaurants pay big bucks for — and marigolds to keep the greenhouse pests away.
He brings his produce to farmers markets, both indoor and outdoor, and sells out consistently because he's one of the few people locally who can offer fresh vegetables in the winter in New Hampshire. He also sells the tilapia at the markets.
"I sell them whole so people have to do their own cleaning," he said. "But I put them on ice and bring them right to market. It's the freshest fish you can get."
Lots of different fish can be used for hydroponics including catfish, rainbow trout, and of course, goldfish, Griffin said.
Some of the plants are grown in a peat-like product called Oasis Horticubes. The seedlings sprout in the cubes, which sit in a trough and are watered once a day through the pipes. Root vegetables are grown in troughs filled with gravel, and the water flows through four times a day. Another planting method Griffin uses relies on small slotted plastic baskets suspended into organic rigid insulation boards that float on the top of the troughs. The roots are constantly exposed to the flow of water and thrive. Beneath the rigid insulation, Griffin plans to raise giant Malaysian prawns that like living beneath the floating roots.
"I built the whole system using organic materials," Griffin said. "And I use 90 percent less water than traditional agriculture."
Griffin's goal is to keep expanding. He hopes to eventually raise around 9,000 tilapia in his two 7,000-gallon tanks and to create breeder colonies so he always has a fresh supply of fish at various stages of growth.
"Basically this whole operation runs itself," he said. "My wife and I both have full-time jobs, but all we need to do is come in in the mornings to check on things and feed the fish. On weekends we plant new seeds and harvest produce to bring to market."